Voltage regulator



Oct. 1, 1940. w. 1 STEVENS VOLTAGE REGULATOR Filed Oct. 20, 1956 Wilfo YL Stevens Patented Oct. 1, 1940 UNITED STATES PATENT OFFICE CanadApplication October 20, 1936, Serial No. 106,688

3 Claims.

This invention relates to a voltage regulator or `controller and has forits specific object the automatic regulation of voltage as generated byan electrical dynamo.

Other objects of my invention are to provide an automatic voltageregulator or controller for electrical generators which shall be smalland compact, oi simple construction and rugged design, and able tomaintain close regulation of voltage and be highly responsive and quickacting.

My invention has been designed more especially for use with alternatingcurrent generators of the smaller sizes whose inher-ent regulation isgenerally very poor as, whenever load is added to such generators, theirvoltage usually falls and fluctuates rapidly, causing lights receivingelectrical energy from such generators to flicker and in some cases toburn very dimly, and it is one of the objects of my invention to obviatethe fluctuation of voltage of such generators by the use of the device Ihave perfected.

My invention is further designed to take care of the worst conditions ofvoltage drop that are caused by the sudden application of inductiveloads such as the switching on of ordinary induction motors, and mydevice is designed to immediately compensate for these suddenly appliedload changes in a simple and efficient manner `by certain inherentcharacteristics which are solely due to the special combinationandassembly of several well-known pieces of apparatus which are soco-ordinated together to produce the results desired.

The complete apparatus presents many improvements, both in structure andperformance, over other forms of apparatus designed to produce somewhatsimilar results.

My invention and the nature of same will be more readily understood byreference to the following speciiication and accompanying drawingforming part of this application, and in Which- Figure 1 is a frontelevation of panel board upon which voltage regulator is mounted.

Figure 2 is a side elevation of panel board mounted upon the end of asmall motor that actuates the moving parts of the voltage regulator.

Figure 3 is a schematic diagram of electrical circuits of voltageregulator.

Figure 4 is a diagrammatic illustration of time duration per revolutionof eccentric that contacts I8 and I9 are engaged to control voltage,viz:

(Cl. 20G- 111) A illustrates time duration of engagement of contacts I8and I9 for light load position.

B illustrates time duration of engagement of contacts I8 and I9 formedium load position.

C illustrates time duration of engagement of contacts I8 and I9 for fullload position.

In the drawing, which illustrates a preferred construction, likenumerals .indicate like parts and the numeral I indicates a constantspeed motor of approximately 900 R. P. M. preferred speed having anon-conducting panel board 2 mounted upon the end frame of the motor.

Upon the face side of the panel board are mounted the various elementscomprising the voltage regulator and the numeral 3 indicates anapertur-ed and vented casing or housing containing a sensitive voltagesolenoid 4 having a movable core 5 so mounted in the centre that itrises and falls with variations of voltage.

To the top of the core 5 is mounted a threadedrod 6 which isco-operatively engaged by one end of a pivotable mounted spring bar 'I.The rod y6 is adjustably mounted upon the end of the spring bar 'I byreason of a pair of helical compression springs 8 mounted upon the rod 6above and below the spring bar 'I and having adjusting nuts 9 actingupon the helical compression springs whereby the end of the spring bar'I is ilexibly tensioned and secured therebetween.

The upper end of the rod E is further suspended by a helical suspensionspring IU that is adjust-v able through an adjusting screw lI mounted inthe outer end of a supporting arm I2 secured upon the face of the panelboard 2 adjacent the top.

The lower end of the movable core 5 is connected to a dashpot rod I3projecting through the bottom of the solenoid casing 3 and terminatingin the dashpot I4 mounted below the bottom of the solenoid casing 3. Thesolenoid 4 is connected to terminals I5 mounted upon Vthe face of thepanel board and having connections on the back thereof.

The inner end of the spring bar 'I is yrigidly secured `to a pivotablesquare block I6 mounted upon the face of the panel board and upon theopposite side of the square block IB is secured another spring bar IIwhich carries an adjustable contact point I8 upon the outer end.

The contact point I8 engages with another movable contact point I9likewise mounted upon the end of another spring bar 20 mounted below thespring bar I'I. The inner end of the springt` bar ZIJ is also rigidlysecured to a-'squaremounting block 2I rmly mounted upon the face of thepanel board.

The spring bar 20 is reinforced by an auxiliary flat spring 22 suitablymounted upon the face of the panel board below the spring bar 2D.

Mounted upon the spring bar 20 intermediately of the square mountingblock 2| and contact I 9 is a bre wearing piece 23 suitably fastened tospring bar 2U which engages with a cam or eccentric 24 mounted upon theend of the motor shaft 25 that projects through the front of the panelboard 2 and imparts movement to the spring bar 2U whenever the motorOperates.

The contact I9 is also provided with an independent up-and-down movementupon the end of the spring bar 20 through being mounted within avertical cylindrical container or cylinder 26 secured upon the end ofthe spring bar 20.

The contact I9 extends and projects through the bottom of the cylinder26 and is engaged by a light spring 2l mounted below the lower side of.the spring bar 2S.

The lower or bottom end of the contact I9 is connected to a flexiblepig-tail connection 28 mounted upon the face of the panel board andhaving a connection at the back of the board.

Conveniently placed upon the face of the panel board is a. controlrheostat 29 that is connected in series with the sensitive voltagesolenoid 4.

Adjacent the bottom of the panel board are three knife switches 30 thatare connected with the solenoid, motor and regulator contact circuits.

The above description is comprehensive or a preferred form ofconstruction of the voltage regulator and below is given the theory ofoperation.

In the schematic wiring diagram of electrica-l circuits shown in Figure3, the part above the dot and dash line represents the circuits of aconventional A. C. generator with the exciter and the lisual rheostats.

To regulate the voltage by hand we may cut in or out resistance ateither or both rheostats 3i or 32, We shall concern ourselves only withrheostat 32 assuming that rheostat 3l is in its best operating position.

Now with 32 in the all in position, we have a minimum voltage conditionof our generator 33 and exciter 34. If we connect a telegraph key acrossto the rheostat 32, we may bring the voltage up to normal by operatingthe key to short out 32. When normal voltage is reached We open the key,thus allowing the voltage to fall somewhat. By rapidly manipulating thekey, we can maintain normal operating voltage under all conditions ofload.

In the voltage regulator we replace the key by the rapidly revolvingeccentric 24 and contacts I8 and I 9. This, however, will only give us asteady voltage at 33 for one value of load, Should the load change, thevoltage at 33 will change. Now, as the load increases, we can obtainsteady voltage at 33 by depressing contact I8, thus causing I8 and I9 tomake contact for a greater part of each revolution of the eccentric orcam 24 and ncreasing the exciter voltage 34.

At the maximum load condition, I8 and I9 will make contact during thewhole of each revolution of eccentric 24, and at minimum load condition,will make contact for a very small part of each revolution or may remainentirely apart.

Instead of operating contact I8 manually, we operate it by suitablemechanical connections to the movable core 5 of the sensitive voltagesolenoid An increase' of load of the main generator 33 causes the core 5of the solenoid to rise slightly, thus increasing the time duration ofcontacts I8 and I9. Regulation of voltage within 1% of normal can bemaintained with this regulator, and Very suddenly applied loads ofinduction motors do not disturb the generator voltage appreciably.

Duration of contact per revolution is shown die.- grammatically atFigure 4 for various generator loads. The amount of contact perrevolution is represented by the position of the eccentric above thedotted line, Compounding, or providing a rising voltage characteristicwith increase of load to compensate for line drop Where it is necessary,is afforded by means of a booster circuit which consists of a coil 35connected in reverse or differentially, and wound on the same core assolenoid 4.

This is connected in series with the secondary of a standard currenttransformer 36 connected into one leg of the same circuit as thepotential or sensitive voltage solenoid. To adjust the amount ofboosting, a suitable adjustable rheostat 37 is connected in parallelwith the current transformer.

Withthis resistance all-in circuit, the boosting eect is at maximum, andwith the resistance al1- out or the current transformer secondaryshortcircuited, the boosting effect is minimum.

'Io regulate voltage on larger machines, two or more contacts aremounted on contact bars I1 and 28, and connected to divide the rheostatcurrent between them to prevent undue arcing of these contacts, or asuitable system of relays may be employed to handle these largecurrents.

As shown in the drawing, the regulator is mounted upon the face of asuitable non-conducting panel 2 which in turn is fastened by suitablebrackets directly to the frame of the driving motor I.

The windings of the solenoid 4 and motor I are connected across themains of the generator 33 whose voltage is to be regulated, eitherdirectly, in the case of low voltage generators, or through potentialreducing transformers in the case of high potential generators.

A condenser of suitable value is shunted across contacts I8 and I9 toprevent undue arcing. By manipulation of rheostat 29 which is connectedin series with the winding of the sensitive voltage solenoid 4,adjustment of the main line voltage is secured.

Having now described my invention and the nature of same, what I claimand desire to be protected in, by Letters Patent, is:

l. In an electric voltage regulator, a panel base, a solenoid mountedvertically on said base, a core within the solenoid and havingprojections beyond both ends of the core, a vibration damper connectedto the lower core projection, a suspension spring to which the uppercore projection is secured, said upper core projection including athreaded rod, a pair of balance springs and a pair of adjusting nuts onsaid rod, a pivoted member including a spring bar one end of whichengages said upper core projection between said balancing springs, saidpivoted member also including a vibrating spring bar having a contactpoint, a second vibrating spring bar also having a contact point tocooperate with the first mentioned contact point, a continuouslyrotating cam located between said vibrating bars for effecting vibrationthereof, and means continuously tending to close said Contact pointstogether.

2. In a voltage regulator for controlling uctuation of voltage of an AC. generator, a panel, a

rotary motor mounted on said panel, a cam on the shaft of said motor, asolenoid mounted on said base, a core in said solenoid, a dashpotconnected to said core to dampen its movements, a suspension spring forsaid core, a member pivoted to said panel and comprising two spring armseach having a free end, means connecting the free end of one of saidarms resiliently with said core, a contact point carried by the free endof the other of said arms, a third spring arm beneath said cam andoperatively engaged thereby, means rigidly mounting one end of saidthird arm on said panel and said third arm having a free end on which ismounted a contact point to cooperate with the first mentioned contactpoint,

and a spring engaging said third arm and continuously tending to pressit toward said cam, all being arranged substantially as and for thepurposes described.

3. In a voltage regulator for controlling fluctuation of voltage of anA. C. generator, a panel, a. rotary motor mounted on said panel, a camon the shaft of said motor, a solenoid mounted on said base, a core insaid solenoid, a dashpot connected to said core to dampen its movements,a suspension spring for said core, a member pivoted to said panel andcomprising two spring arms each having a free end, means connecting thefree end of one of said arms resiliently with said core, a contact pointcarried by the free end of the other of said arms, a third spring armbeneath said cam and operatively engaged thereby, means rigidly mountingone end of said third arm on said panel and said third arm having a freeend on which is mounted a contact point to cooperate with the rstmentioned contact point, and a spring engaging said third arm andcontinuously tending to press it toward said cam, a tubular socket fixedto said third arm in which socket said last named contact point islocated and through the bottom of which the same contact projects, aflexible conductor one end of which is mounted on said panel and theother end of which is secured to the projecting end of the third armscontact, and a spring carried by said third arm for engaging said thirdarms contact to urge it in a direction toward the iirst mentionedcontact.

WILFORD L. STEVENS.

